[request] simple "pass" or "technique" interface for rendering...

It would just rocks if SIO2 could support "techniques", for doing multipass effects.
A technique would be an object with a pass count and a setup method.
When activated, the engine would call the setup method then render the requested objects, for each pass = [1 .. pass count].

You can easily do that yourself you don't need sio2 for that... Sio2 give you access to the machine state implemented behind the objects and material and you have access to the color buffer so... Anyway from my opinion multiple pass on the device is not an option due to the limited fill rate...